for us tonight. ben? >> reporter: scott, the alleged shooter is something of a blank slate-- no criminal record and, for someone his age, 23, he's posted very little online. his family says they're shocked and investigators are trying to figure out why he targeted t.s.a. officers here in this terminal at l.a.x. today, f.b.i. agents were at the apartment where paul anthony ciancia has been living outside of los angeles. they escorted one of his roommates to his cartelling reporters they needed to interview him. armando basco is his neighbor. >> we never thought -- he's a very quiet guy. >> reporter: since being wheeled into the hospital friday, ciancia has been heavily sedated and unable to talk. this picture was taken moments after police shot him to end the rampage. that's when they say ciancia told them that he acted alone and was dropped off at the airport by a friend. police also found a hand-written letter in his bag. in its ciancia wrote he made the conscious decision to try to kill multiple t.s.a.